I've successfully created a 'Day' and 'Night' photoreal with .TIFF blend maps but I have a problem.

On the 'Day' .bmp I made shadows under some static aircraft / gate guards which display fine during the day.

For the 'Night' .bmp I simply removed the shadows, but they still show at Night, Dawn and Dusk... It's as though the 'Day' photoreal is still showing through at night somehow.

I know the Night photoreal is displaying ok because I added some spotlight / streetlight 'splashes' to give the impression of night lighting and these show just fine. It's just that the shadows under the aircraft are still there at night!

No idea why you are getting that shadow at night, unless Resample is, in fact, applying your Light Map to the Day Map when creating the Night variant. If so, then you can either live with it or remove the shadows in the Day Map to avoid the problem at night. But, what a shame that would be since the shadow looks great.

On the other hand, you do have that area illuminated at night and lamps would cast a shadow below the airplane, so this is very realistic.